Genetics Northern California

Glossary

TermDescription
Talipes equinovarusLatin term for club foot; a congenitally deformed foot which is twisted out of shape or position.
Tay Sachs disease

A fatal degenerative disease of the nervous system due to a deficiency of hexosaminadase A, causing mental retardation, paralysis, blindness and death by 3-4 years of age. Found most commonly in people of Ashkenazi Jewish and French Canadian ancestry.

Teratogen

An agent that produces or raises the incidence of birth defects.

ThalassemiasA group of hemolytic anemias which are caused by the decreased production of the alpha, beta or gamma chains of hemoglobin (oxygen producing part of the red blood cell). Most commonly found in individuals of Asian or Mediterranean ancestry.
Transfatty acidsThese are usually formed during the process of hydrogenation.
Translation

The creation of a protein derived from messenger RNA

Translocation

The transfer of one segment of one chromosome to another chromosome (ie reciprocal and Robertsonian).

TriglyceridesA compound consisting of three molecules of fatty acid esterified to glycerol and is a neutral fat synthesized from carbohydrates for storage in animal fat cells.
Triplet repeat (trinucleotide repeat)

A pattern where a given set of nucleotides is repeated multiple times ( many times more than in an individual without the condition)which causes a specific disease.

Trisomy

The state of having three copies of a given chromosome instead of the usual two.

Trisomy 13

A serious form of mental retardation where the individual carries three copies of chromosome 13, instead of the usual two copies. Severe mental retardation, severe heart disease, and a lifespan usually less than one year characterize the condition.

Trisomy 18A chromosome condition whereby the individual has three instead of two copies of chromosome 18. Individuals with Trisomy 18 have severe mental retardation and usually severe heart disease with 90% dying within the first year of life.
Trisomy 21

Scientific term for Down Syndrome. The individual has three copies of chromosome 21 instead of the usual two copies (one from each parent).

Truncate

The premature termination of a protein product.

Tumor

Abnormal mass of tissue that can be benign or malignant.

Tumor suppressor geneGenes that normally restrain cell growth but, when missing or inactivated by mutation allow the cell to grow uncontrolled.
Two hit hypothesis (Knudson's model)

Hypothesis that malignant transformation of cells occurs after at least two cellular mutation events or the "two hit theory".